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If this admission constitute an objection to Political Economy,* it is equally an objection to astronomy,
·* Mr. Jennings (Natural Elements of Political Economy, p. 4) disposes of this defence of economic doctrine in the following fashion :“The doubting pupil is now dismissed with the assurance that the principles of Political Economy which he has been taught, if not true, have a tendency to be true; that if found imperfectin the abstract [quære, concrete l] they are perfect in the concrete [quære, abstract ?], and that an allowance must always be made for the influence of disturbing causes."
I don't know that any further reply need be made to this than that given in the text, namely, that whatever be the value of the objection, it applies to the whole body of physical as well as moral science. In no other sense is a physical law true than as expressing “a tendency” influencing matter. Whether the result in any given case be such as the law or tendency in question would lead us to expect, will depend, in the physical as in the moral world, upon the other causes which happen to coexist with it. The reason that attention has been drawn more to the influence of disturbing causes in the political and moral than in the physical sciences is sufficiently obvious. In those physical sciences which are sciences of observation, as astronomy, the principles are few in number and perfectly definite in character; while in those physical sciences, as, e. g. chemistry, in which the principles are more numerous and complex, we can avail ourselves of experiment. In the former case, all the causes influencing the result are known and their effect may be calculated ; in the latter, all that are not required may be eliminated. But in the moral and political sciences in which we have to deal with human interests and passions, the agencies in operation at any given time in any given society are numerous, while, being in this case precluded from experiment, we are unable to prepare the conditions beforehand with a view to preserving the necessary cæteris paribus.
A chemist states that certain salts when brought into the same solution will react on each other, and yield an insoluble precipitate. A Political Economist states that certain causes have certain effects on the production and distribution of wealth. Whether either of these statements be true in a given case, will depend upon whether the condition cæteris paribus (expressed or implied) be fulfilled. The chemist, however, can produce the necessary condition by excluding from
mechanics, and to all those physical sciences which combine deductive with inductive reasoning.
the solution every thing that would interfere with the result which he predicts; while the political economist can only bring his principle into operation in human societies as he finds them. In the case, therefore, of an economic principle the result is almost always modified by causes different from that respecting which the assertion called an economic law is made, while in physical science we can obtain simple results, or complex only to the extent which may suit our purpose.
OF THE LOGICAL METHOD OF POLITICAL ECONOMY.
In adverting, in the opening of this course, to the differences of opinion now existing respecting many fundamental principles in Political Economy, I stated that these discrepancies appeared to me to be chiefly traceable to the more loose and popular method of treating economic questions which has of late years come into fashion ;—and I further stated that this change in the character of economic discussions was, as I conceived, mainly attributable to the practical success of economic principles in the experiment of free trade—a success which, while it attracted a new class of adherents to the cause of Political Economy, furnished its advocates also with a new description of arguments.
The method which we pursue in any inquiry must be determined by the nature and objects of that inquiry. I was thus led in my opening lectures to consider the nature and objects of Political Economy. In the present and following lectures I proceed to discuss the method which, having regard to what
Political Economy proposes to accomplish, it is proper to pursue in its investigations.
Let me recall briefly the description I have given of the nature and objects of Political Economy. You will remember I defined Political Economy as the science which investigates the laws of the production and distribution of wealth, which result from the principles of human nature as they operate under the actual circumstances of the external world. I also stated that those mental principles and physical conditions are taken by the Political Economist as ultimate facts, as the premises of his reasonings, beyond which he is not concerned to trace the causes of the phenomena of wealth. I next considered the nature of those ultimate facts, physical and mental, and found that, although so numerous as to defy distinct specification, there are yet some, the existence and character of which are easily ascertainable, of such paramount importance in relation to the production and distribution of wealth, as to afford a sound and stable basis for deducing the laws of those phenomena. The principal of these I stated to be, ist, the desire for wealth, and aversion to labour implanted in human beings; 2ndly, the principles of population as derived from the physiological character of man and his mental propensities; and 3rdly, the physical qualities of the natural agents, more especially land, on which human industry is exercised. I also showed you that the most important of the subordinate principles affecting the production and distribution of wealth, which come in
to modify and sometimes to reverse the operation of the more cardinal principles, are also capable of being ascertained and appreciated, with sufficient accuracy at least to be taken account of in our reasonings, if not to be made the premises of future deductions ; and of these also I gave several examples.
This, then, being the character of Political Economy, we have to consider by what means the end which it proposes—the discovery of the laws of the production and distribution of wealth-may be most effectually promoted. The guide to which we here naturally turn is the analogy of the physical sciences. In the application of this analogy, however, we must be careful not to be misled by an appearance of agreement where the circumstances are essentially dissimilar. The propriety of the method must in each case be ultimately determined by the character of the evidence which is in each case available, and we shall find that in this respect the physical sciences and Political Economy are by no means on the same footing.
The first attempts at physical discovery have always been made by the observation and classification of physical phenomena. This classification has generally at first taken place according to the most obvious relations which present themselves to our notice in physical objects. Further examination and analysis of the results thus obtained have led to the discovery of more important and intimate relations, which have been made the grounds of higher and more comprehensive inductions ; and this process has been con